Silicone polyethers have long been used as slip additives, defoaming agents and many other industrial applications. They are used in personal care for use as conditioners, emollients and emulsifiers and invert emulsifiers and many other applications.
Many types of emulsifiers are available in the market that act as an invert emulsifier. Silicone based alkyl polyethers such as Silube J208-812 and J208-612, available from Siltech Corp in Toronto, have been used in this application. These silicone based alkyl polyethers act as low to medium HLB emulsifiers to make invert w/o emulsions. In addition they provide a good skin feel and water resistance. HLB is a measurement of the hydrophilic/hydrophobic balance in a surfactant and is normally based on PEG (polyglycol) compounds that have a large portion of organic and/or silicone moiety along with the PEG portion. Most invert emulsions use a surfactant with low to medium HLB.
U.S. Pat. No. 4,698,178 to Huttinger et al describes the use of silicone polyethers that have separate alkyl and polyether pendant groups for use as water in oil emulsifiers.
U.S. Pat. No. 6,133,370 to Gutek et al describes using Phenylpropyl based silicone polyethers as emulsifiers.
In each case, the silicone contains PEG groups. There is concern about dioxane and ethylene oxide levels contained in PEG compounds and also the genotoxicity of PEG based products. Because of safety concerns surrounding the use of PEG based products, there is a desire to make w/o and/or w/si emulsions using a silicone based invert emulsifier that does not contain any PEG groups.
U.S. Pat. No. 3,381,019 to Morehouse et al describes the use of a multi hydroxy silicone made by the reaction of a silicone hydride reacted with trimethylolpropane monoallylether. This patent describes applications in urethane foam and as defoamers, but not as w/o or w/si emulsifiers.
U.S. Pat. No. 5,916,992 to Wilt et al also describes the use of multi hydroxy silicone made by the reaction of a silicone hydride reacted with trimethylolpropane monoallylether for use in industrial coatings.
Silicones with propyl alcohol groups made from the reaction of silicone hydrides with allyl alcohol are known in the industry such as those provided by Siltech under the brand Silmer OH. These have been tested as invert emulsifiers, but the products do not have enough hydrophilicity to be useful as a w/o or w/si emulsifiers even in high concentrations of hydroxy groups.